Language and reading deficits associated with neurofibromatosis type 1: Evidence for a not-so-nonverbal learning disability

Neurofibromatosis Type 1 (NF1) is a common genetic disorder for which nonverbal learning disability (NLD) is frequently reported. In this study, verbal and nonverbal skills among NF1 school-age children and their unaffected siblings were assessed. Results of matched-paired comparisons were consistent with previous reports of visuospatial deficits in NF1. The results also indicate verbal weaknesses in NF1, including deficits in vocabulary and phonological awareness, and a positive correlation-among the NF1 group only - between performance on the Judgment of Line Orientation test (Benton, 1983) and several verbal tasks. The verbal deficits indicate that NLD may not be an accurate construct with which to describe the NF1 phenotype. Children with NF1 manifested skills deficits in mathematics and reading even though the incidence of discrepancy-based reading disability (RD) or mathematics disability (MD) did not differ across groups. The NF1 profile illustrates the conceptual difficulty underlying discrepancy-based RD because it appears that the language disorder in neurofibromatosis influences both measures used (achievement and IQ) to calculate the discrepancy.